Bevel gear product tooth root transition structure modeling method and bevel gear

Abstract

The invention relates to the technical field of bevel gear manufacturing, in particular to a bevel gear product tooth root transition structure modeling method and a bevel gear, and the method comprises the following steps: S1, drawing an intersection point of a root cone line and a pitch cone line of the bevel gear; s2, respectively drawing involutes at the large end position and the small end position by taking the intersection point as a reference zero point of the tooth space width; s3, a first smooth curve and a second smooth curve are drawn at the large end position and the small end position respectively, and the first smooth curve and the second smooth curve coincide with the bottom end points of the corresponding involutes and are tangent to the involutes; s4, the first smooth curve and involutes on the two sides of the first smooth curve form a first structural curve, and the second smooth curve and involutes on the two sides of the second smooth curve form a second structural curve; and S5, drawing a curved surface through the first structural curve and the second structural curve. According to the method, the problem that the gear forging tooth root fillet is prone to cracking can be solved, and the service life of the straight bevel gear tooth profile hot forging die is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of bevel gear manufacturing, and in particular to a bevel gear product tooth root transition structure modeling method and a bevel gear. Background Art

[0002] Few people pay attention to the root transition design of spur bevel gears used in differentials, but the transition fillet of the root will have a great impact on the strength of the root. The original differential spur bevel gears were processed by planing or circular drawing, and the root transition structure was determined by the corresponding tool. The development of precision forging technology has eliminated the planing or circular drawing production process for the production of differential spur bevel gears. The advantages of forging spur bevel gears are high processing efficiency and the mold used in the forging process comes from the three-dimensional modeling of spur bevel gears. The root transition structure is completed in the three-dimensional drawing software, such as Figure 1 At present, the root transition structure of most spur bevel gears is to directly round the root part to form a round chamfer 9. The disadvantage of this modeling is that when the base circle diameter is quite different from the root circle diameter, there is still a part of the straight edge after the root part is rounded 10. This structure is prone to straight edge of the root during the forging process, and the finishing is not in place. In addition, the root part of the bevel gear product is prone to fatigue fracture, and the strength of the root part needs to be improved and strengthened. Summary of the invention

[0003] In order to solve the problem in the prior art that the rounded corners at the bottom of the gear easily cause straight edges at the tooth roots, the present invention provides a bevel gear product tooth root transition structure modeling method and a bevel gear for improving fatigue fracture caused by straight edges at the tooth roots of bevel gears.

[0004] The technical solution adopted by the present invention to solve its technical problem is:

[0005] A method for modeling a tooth root transition structure of a bevel gear product comprises the following steps:

[0006] S1: Draw the intersection of the root cone line and the pitch cone line of the bevel gear;

[0007] S2: Taking the intersection as the reference zero point of the tooth width, draw involutes at the large end and the small end respectively;

[0008] S3: Draw a first smooth curve and a second smooth curve at the large end position and the small end position respectively, the first smooth curve and the second smooth curve coincide with the bottom endpoints of the corresponding involute and are tangent to the involutes on both sides;

[0009] S4: Delete the first smooth curve and the second smooth curve above the bottom endpoint of the involute, the first smooth curve and the involutes on both sides thereof constitute a first construction curve, and the second smooth curve and the involutes on both sides thereof constitute a second construction curve;

[0010] S5: Draw a surface through the first construction curve and the second construction curve.

[0011] Furthermore, in S2, drawing the involute at the large end position and the small end position includes the following methods:

[0012] S21: If the position of the small end is determined first and the involute is drawn, the bottom ends of the involutes on both sides of the small end are respectively connected to the reference zero point to form two short lines, and the two short lines are extended in a direction away from the reference zero point, the involute of the large end is determined according to the groove width of the large end position, and the bottom ends of the involutes on both sides of the large end position are connected to the extension line;

[0013] S22: If the large end position is determined first and the involute is drawn, the bottom ends of the involutes on both sides of the large end position are respectively connected to the two reference points to form two long lines, the involute of the small end is determined according to the groove width of the small end position, and the bottom ends of the involutes on both sides of the small end are connected to the long lines.

[0014] Furthermore, the first smooth curve and the second smooth curve are quadratic curves.

[0015] Furthermore, the surface drawn in S5 is a mesh surface.

[0016] The present invention also provides a bevel gear, the tooth groove of the bevel gear is obtained by the above-mentioned bevel gear product tooth root transition structure modeling method.

[0017] Furthermore, the bevel gear is produced by forging.

[0018] Beneficial effects:

[0019] (1) The spur bevel gear tooth root transition modeling method of the present invention forms an integrated tooth groove surface by constructing a curved surface through a curve, and then completes the single tooth modeling through functions such as stretching and trimming, and then establishes a matrix model, and finally forms a full tooth model. Compared with the traditional spur bevel gear tooth root chamfer structure, it can ensure a smooth transition at the bottom of the tooth groove, greatly improve the strength of the tooth root part, and improve the problem of easy cracking of the gear forging tooth root fillet, and improve the life of the spur bevel gear tooth profile hot forging die;

[0020] (2) The present invention can solve the problem of finishing straight edges occurring during the forging process, and is beneficial to finishing in the forming process of warm forging and finishing. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0022] Figure 1 It is a schematic diagram of a tooth groove structure with straight edges in the prior art;

[0023] Figure 2 A schematic diagram of a small end involute and a short connecting line is drawn for Example 1;

[0024] Figure 3 A schematic diagram of an extension line is drawn for Example 1;

[0025] Figure 4 A schematic diagram of a large end involute drawn on an extended line of Example 1;

[0026] Figure 5 A schematic diagram of a large end involute and a long connecting line is drawn for Example 2;

[0027] Figure 6 A schematic diagram of drawing a small-end involute on a long connecting line for Example 2;

[0028] Figure 7 A schematic diagram for drawing a first smooth curve and a second smooth curve;

[0029] Figure 8 A schematic diagram of drawing a surface through a first construction curve and a second construction curve;

[0030] Fig. 9 It is a solid schematic diagram of the tooth groove surface;

[0031] Fig.10 It is a schematic diagram of the structure of a single tooth groove;

[0032] Fig.11 This is a schematic diagram of the structure of a bevel gear product.

[0033] 1. Reference zero point, 11. Root cone line, 12. Nodal cone line, 2. First smooth curve, 3. Second smooth curve, 4. First construction curve, 5. Second construction curve, 6. Short connecting line, 7. Extension line, 8. Long connecting line, 9. Fillet chamfer. 10. Straight edge. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0036] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the present invention. Meanwhile, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0037] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the devices or elements referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention. The directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0038] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0039] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0040] The present invention provides a method for modeling a tooth root transition structure of a bevel gear product, comprising the following steps:

[0041] S1: Draw the intersection of the root cone line 11 and the pitch cone line 12 of the bevel gear;

[0042] S2: Take the intersection as the reference zero point 1 of the tooth width, and draw involutes at the large end and the small end respectively;

[0043] In S2, there are two ways to draw involutes at the large end position and the small end position:

[0044] Embodiment 1:

[0045] S21: Figures 2 to 4 If the small end position is determined first and the involute is drawn, the bottom ends of the involutes on both sides of the small end are respectively connected to the reference zero point 1 to form two short lines 6, and the two short lines 6 are extended in the direction away from the reference zero point 1. The involute of the large end is determined according to the groove width of the large end position, and the bottom ends of the involutes on both sides of the large end position are connected to the extension line 7. This method is equivalent to taking the reference zero point 1 as the starting point and extending it proportionally to draw the involute of the large end position according to the involute of the small end position.

[0046] Embodiment 2:

[0047] S22: Figures 5-6If the large end position is determined first and the involute is drawn, the bottom ends of the involutes on both sides of the large end position are respectively connected to the two reference points to form two long lines 8, and the involute of the small end is determined according to the groove width of the small end position, and the bottom ends of the involutes on both sides of the small end are connected to the long line 8. This method is equivalent to referring to the zero point 1 as the end point, which is similar to the principle of Example 1, and the involute of the small end position is drawn according to the involute of the large end position.

[0048] S3: When the involutes at the large end position and the small end position are drawn, Figure 7 , draw a first smooth curve 2 and a second smooth curve 3 at the large end position and the small end position respectively, the first smooth curve 2 and the second smooth curve 3 coincide with the bottom endpoints of the corresponding involute and are tangent to the involutes on both sides;

[0049] S4: Delete the first smooth curve 2 and the second smooth curve 3 above the bottom endpoint of the involute (if the first smooth curve 2 and the second smooth curve 3 do not exceed the bottom endpoint of the involute, the deletion step is omitted), the first smooth curve 2 and the involutes on both sides thereof constitute a first construction curve 4, and the second smooth curve 3 and the involutes on both sides thereof constitute a second construction curve 5;

[0050] S5: Figure 8 , a surface is drawn by the first construction curve 4 and the second construction curve 5. Preferably, the first smooth curve 2 and the second smooth curve 3 are quadratic curves. The drawn surface may be selected but not limited to a mesh surface. As an implementation method, a mesh ruled surface may be selected in UG drawing software, and the first construction curve 4 and the second construction curve may be selected to generate a mesh surface.

[0051] The present invention also provides a bevel gear, wherein the tooth groove of the bevel gear is obtained by the above-mentioned bevel gear product tooth root transition structure modeling method, and the obtained tooth groove structure is as follows: Fig. 9 and Fig.10 As shown, the bevel gear of the present invention is produced by forging.

[0052] In the 3D drawing software UG, the 3D digital model of the spur bevel gear is completed using curves, sketches, straight lines, rotation, stretching, trimming and other functional features. The improvement is that the tooth root of the spur bevel gear 3D model is connected with the tooth profile involute of the two tooth surfaces by a quadratic curve to form an overall tooth groove curve, thereby generating an overall tooth groove surface, eliminating the tooth root fillet feature and avoiding the complex calculation of the transition connection between the curve and the involute.

[0053] Traditional modeling is to first perform tooth shape modification, then complete single tooth modeling through functions such as stretching and trimming, then build a base model, and finally form a full tooth model. Now the modeling process is changed to first perform tooth shape modification, then complete integrated tooth groove surface modeling through functions such as straight lines and trimming, then build a base model, and finally form a full tooth model. Fig.11 Eliminating the chamfer at the root of the tooth and changing it to a quadratic curve transition can improve the problem of easy cracking of the root fillet of the gear forging and increase the life of the tooth hot forging die, which is of great significance for the manufacturing of tooth die.

[0054] The above are only preferred specific implementation modes of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for modeling the tooth root transition structure of a bevel gear product, characterized in that: The following steps are involved: S1: Draw the intersection of the root cone line (11) and the pitch cone line (12) of the bevel gear; S2: Taking the intersection point as the reference zero point of the tooth width (1), draw involutes at the large end position and the small end position respectively; S3: Draw a first smooth curve (2) and a second smooth curve (3) at the large end and the small end, respectively. The first smooth curve (2) and the second smooth curve (3) coincide with the bottom endpoints of the corresponding involutes and are tangent to the involutes on the corresponding two sides. S4: Delete the first smooth curve (2) and the second smooth curve (3) above the bottom end point of the involute, the first smooth curve (2) and the involutes on both sides thereof constitute a first construction curve (4), and the second smooth curve (3) and the involutes on both sides thereof constitute a second construction curve (5); S5: Draw a surface using the first construction curve (4) and the second construction curve (5).

2. A bevel gear product tooth root transition structure modeling method according to claim 1, characterized in that: In S2, the following methods are used to draw involutes at the large end position and the small end position: S21: If the position of the small end is determined first and the involute is drawn, the bottom ends of the involutes on both sides of the small end are respectively connected to the reference zero point (1) to form two short connecting lines (6), and the two short connecting lines (6) are extended in a direction away from the reference zero point (1), the involute of the large end is determined according to the groove width of the large end position, and the bottom ends of the involutes on both sides of the large end position are connected to the extension line (7); S22: If the large end position is determined first and the involute is drawn, the bottom ends of the involutes on both sides of the large end position are respectively connected to the two reference points to form two long lines (8), the involute of the small end is determined according to the groove width of the small end position, and the bottom ends of the involutes on both sides of the small end are connected to the long lines (8).

3. A bevel gear product tooth root transition structure modeling method according to claim 1, characterized in that: The first smooth curve (2) and the second smooth curve (3) are quadratic curves.

4. A bevel gear product tooth root transition structure modeling method according to claim 1, characterized in that: The surface drawn in S5 is a mesh surface.

5. A bevel gear, characterized in that: The tooth groove of the bevel gear is obtained by the bevel gear product tooth root transition structure modeling method as described in any one of claims 1 to 4.

6. The bevel gear according to claim 5, characterized in that: The bevel gear is produced by forging.

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